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See detailMulti-period vehicle allocation with uncertain transportation requests
Crama, Yves ULg; Pironet, Thierry ULg

E-print/Working paper (2017)

This work investigates optimization techniques for a multi-period vehicle allocation problem with uncertain requests. A company owning a limited fleet of trucks attempts to maximize its operational profit ... [more ▼]

This work investigates optimization techniques for a multi-period vehicle allocation problem with uncertain requests. A company owning a limited fleet of trucks attempts to maximize its operational profit over an infinite horizon by optimally assigning transportation orders to the vehicles. Its profit stems from profits collected when transporting full truckloads, minus costs incurred when waiting or when moving unladen. The stochastic component of the problem arises from the uncertainty on the realization of each transportation order. The methodology is based on optimizing decisions for deterministic scenarios. Several policies are generated in this way, either by simple heuristics, or by more complex approaches, such as consensus and restricted expectation algorithms, or from network flow formulations over subtrees of scenarios. Myopic and a-posteriori deterministic optimization models are used to compute bounds allowing for performance evaluation. Numerical experiments are performed on various instances featuring different numbers of orders, graph sizes, sparsity, and probability distributions, and the performance of the algorithms is assessed by statistical tests. The robustness of various policies with respect to erroneous evaluations of the probability distributions is also analyzed. [less ▲]

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See detailCluster growth in driven granular gases
Noirhomme, Martial ULg; Ludewig, François; Vandewalle, Nicolas ULg et al

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2017)

We investigate numerically and theoretically the internal structures of a driven granular gas in cuboidal cell geometries. Clustering is reported and particles are classified as gaseous or clustered via a ... [more ▼]

We investigate numerically and theoretically the internal structures of a driven granular gas in cuboidal cell geometries. Clustering is reported and particles are classified as gaseous or clustered via a local packing fraction criterion based on a Voronoi tessellation. We observe that small clusters arise in the corners of the box, elucidating early reports of partial clustering. These aggregates have a condensation-like surface growth. When a critical size is reached, a structural transition occurs and all clusters merge together, leaving a hole in the center of the cell. This hole then becomes the new center of particle capture. Taking into account all structural modifications and defining a saturation packing fraction, we propose an empirical model for the cluster growth. [less ▲]

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See detailFanfictions, blogs, web-poetry et jeux vidéo
Dupont, Bruno ULg; Barnabé, Fanny ULg

Scientific conference (2017, February 23)

Comment s'élaborent les cultures des fans ? Quels rapports se créent entre auteur et lecteur-créateur ? Quels sont les enjeux de ces cultures participatives et pourquoi est-il intéressant de les étudier ... [more ▼]

Comment s'élaborent les cultures des fans ? Quels rapports se créent entre auteur et lecteur-créateur ? Quels sont les enjeux de ces cultures participatives et pourquoi est-il intéressant de les étudier aujourd'hui ? [less ▲]

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See detailTre segnalazioni su Sciascia. Città, solitudini, saggismo e invenzione.
Curreri, Luciano ULg

Article for general public (2017)

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See detailPratiques du détournement dans la bande dessinée
Dejasse, Erwin ULg

Scientific conference (2017, February 22)

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See detailEnergy Efficiency in the Romanian Residential Building Stock: A Literature Review
Muresan, Adina Ana; Attia, Shady ULg

in Renewable and Sustainable Energy Reviews (2017), 74

The building sector in Romania is dominated by residential buildings that are old and have poor thermal performance. As member of the European Union, Romania has to reach the objectives imposed by the ... [more ▼]

The building sector in Romania is dominated by residential buildings that are old and have poor thermal performance. As member of the European Union, Romania has to reach the objectives imposed by the Directive 2009/28/EC and to fulfill the requirements of the Energy Performance of Buildings Directive (EPBD) by year 2020. To reach the 2020 objectives, the old buildings from the Romanian building stock should be rehabilitated and the new buildings should be designed according to the latest thermal performance characteristics. The following paper presents the literature review of building energy performance in Romania. The purpose of the literature review analysis is to provide an overview on current building energy efficiency in Romania. The paper also presents future perspectives on implementation of high performance buildings such as the Passive House (PH), nearly Zero Energy Buildings (nZEB) and Net Zero Energy Buildings (NZEB). The reviewed publications and case studies are classified under three categories: policy and regulations, technology and feasibility. Finally, the paper presents a holistic perspective on the Strength, Weakness, Opportunities and Threats (SWOTs) of energy efficiency in Romania's residential building sector. [less ▲]

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See detailA Multiplatform Experiment to Unravel Meso- and Submesoscale Processes in an Intense Front (AlborEx)
Pascual, Ananda; Ruiz, Simon; Olita, Antonio et al

in Frontiers in Marine Science (2017)

The challenges associated with meso- and submesoscale variability (between 1 and 100 km) require high-resolution observations and integrated approaches. Here we describe a major oceanographic experiment ... [more ▼]

The challenges associated with meso- and submesoscale variability (between 1 and 100 km) require high-resolution observations and integrated approaches. Here we describe a major oceanographic experiment designed to capture the intense but transient vertical motions in an area characterized by strong fronts. Finescale processes were studied in the eastern Alboran Sea (Western Mediterranean) about 400 km east of the Strait of Gibraltar, a relatively sparsely sampled area. In-situ systems were coordinated with satellite data and numerical simulations to provide a full description of the physical and biogeochemical variability. Hydrographic data confirmed the presence of an intense salinity front formed by the confluence of Atlantic Waters, entering from Gibraltar, with the local Mediterranean waters. The drifters coherently followed the northeastern limb of an anticyclonic gyre. Near real time data from acoustic current meter data profiler showed consistent patterns with currents of up to 1 m/s in the southern part of the sampled domain. High-resolution glider data revealed submesoscale structures with tongues of chlorophyll-a and oxygen associated with the frontal zone. Numerical results show large vertical excursions of tracers that could explain the subducted tongues and filaments captured by ocean gliders. A unique aspect of AlborEx is the combination of high-resolution synoptic measurements of vessel-based measurements, autonomous sampling, remote sensing and modeling, enabling the evaluation of the underlying mechanisms responsible for the observed distributions and biogeochemical patchiness. The main findings point to the importance of fine-scale processes enhancing the vertical exchanges between the upper ocean and the ocean interior. [less ▲]

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See detailAncient Egyptian philology: The digital turn. Current projects and future perspectives for the study of Ancient Egyptian texts
Polis, Stéphane ULg; Razanajao, Vincent ULg

Conference (2017, February 21)

Use of Information Technologies in Egyptology can be traced back to the early 1960s, when first efforts were made in documenting Meroitic scripts or emblematic corpora such as the Pyramid Texts. With the ... [more ▼]

Use of Information Technologies in Egyptology can be traced back to the early 1960s, when first efforts were made in documenting Meroitic scripts or emblematic corpora such as the Pyramid Texts. With the rise of the Digital Humanities in the mid-2000s, many new academic projects that implement IT solutions not only as a way to manage and present data, but also to produce, process and analyse the material, have come to light in the field. The aim of this paper is to give a survey of current digital projects related to the study of ancient Egyptian and Coptic texts. Our goal is not to be exhaustive, but to discuss the methods and tools that are being used and to describe the variety of scholarly practices. The first set of projects to be examined are those related to digital text editions and annotated corpora (including the types of representation format). Second, the question of how to handle the complex writing systems of Ancient Egypt will be addressed by looking at projects that focus on encoding (Manuel de Codage vs Unicode), on establishing hieroglyphic sign-lists (the Thot-Sign-List), on palaeographical databases and on ways to OCRize original texts efficiently. The issue of interoperability and data sharing will then be investigated through a presentation of several related projects working on a XML/TEI interchange format as well as on digital resources for enabling a Linked Open Data approach to the ancient Egyptian written material (http://thot.philo.ulg.ac.be/). Finally, we will argue in favour of a coherent data model so that encoding of data and metadata is done in the most effective way. [less ▲]

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See detailConception of a near-infrared spectrometer for ground-based observations of massive stars
Kintziger, Christian ULg; Desselle, Richard ULg; Loicq, Jerôme ULg et al

in Journal of Astronomical Telescopes, Instruments, and Systems (2017), 3(1), 015002

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument for stellar astrophysics. Starting from the derivation of theoretical relationships from the ... [more ▼]

In our contribution, we outline the different steps in the design of a fiber-fed spectrographic instrument for stellar astrophysics. Starting from the derivation of theoretical relationships from the scientific requirements and telescope characteristics, the entire optical design of the spectrograph is presented. Specific optical elements, such as a toroidal lens, are introduced to improve the instrument’s efficiency. Then the verification of predicted optical performances is investigated through optical analyses, such as resolution checking. [less ▲]

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See detailUne architecture novatrice
Charlier, Sébastien ULg

Conference given outside the academic context (2017)

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See detailContribution à la mise en place d’une plateforme de transgénèse chez la volaille domestique: culture, cryopréservation et ingénierie génétique de cellules germinales primordiales.
Tonus, Céline ULg

Doctoral thesis (2017)

Primordial germ cells (PGCs) are the intermediate of choice for domestic fowl transgenesis and genome editing. These can support large transgenes insertions and, as precursors of the germline, can ... [more ▼]

Primordial germ cells (PGCs) are the intermediate of choice for domestic fowl transgenesis and genome editing. These can support large transgenes insertions and, as precursors of the germline, can transmit a genetic modification to the next generation. Moreover, given the difficulties for cryopreserving avian gametes (spermatozoa and, above all, oocytes), PGCs represent the material of choice for germplasm preservation in these species. Despite the obvious advantages of PGCs use, recently described related technologies appear generally as more difficult to pursue, and as less effective than expected. In this context, we have developed and optimized some of them which appear as essential for carrying complex chicken genome engineering projects. We first focused on improving the effectiveness of culture and cryopreservation of PGCs. By developing a culture method in inserts, ending up with an efficiency close to 40 %, we were able to isolate and long-term cultivate chickens PGCs from 3 commercial breeds and 2 Belgian endangered local breeds. The cells showed all the characteristics of the PGCs in terms of morphology, markers' expression and gonadal migration. We also applied a cryopreservative vitrification method, which showed results superior to those obtained by conventional slow freezing. During the last part of this work, we genetically engineered PGCs to obtain stable transfectants expressing GFP. These transfectants allowed us to examine long-term gonadal colonization and germline transgene transmission. We also tested a Cre recombinase-mediated site-specific cassette exchange method. As a final result, we have developed the methods and know-how mandatory to allow efficient harvesting, expansion, genetic engineering, reimplantation and cryopreservation of chicken PGCs, and we have shown the possibility of germline transmission of a long term cultured and genetically modified PGCs line. [less ▲]

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See detailDécoder les verrous d’apprentissage d’une discipline
Verpoorten, Dominique ULg; Devyver, Julie ULg; Duchâteau, Dominique ULg et al

Conference (2017, February 21)

L’ULg a conduit une expérience pilote avec quelques enseignants. Elle vise à estimer le potentiel didactique et pédagogique d’un travail sur les « verrous d’apprentissage » (traduction délibérément ... [more ▼]

L’ULg a conduit une expérience pilote avec quelques enseignants. Elle vise à estimer le potentiel didactique et pédagogique d’un travail sur les « verrous d’apprentissage » (traduction délibérément adaptée de « bottleneck ») pour lutter contre l’échec, ou plutôt pour relever le défi de l’intégration intellectuelle du plus grand nombre. [less ▲]

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See detailThe importance of pollen chemistry in evolutionary host shifts of bees
Vanderplanck, Maryse ULg; Vereecken, Nicolas; Grumiau, Laurent et al

in Scientific Reports (2017)

Although bee-plant associations are generally maintained through speciation processes, host shifts have occurred during evolution. Understanding shifts between both phylogenetically and morphologically ... [more ▼]

Although bee-plant associations are generally maintained through speciation processes, host shifts have occurred during evolution. Understanding shifts between both phylogenetically and morphologically unrelated plants (i.e., host-saltation) is especially important since they could have been key processes in the origin and radiation of bees. Probably far from being a random process, such host-saltation might be driven by hidden constraints associated with plant traits. We selected two clades of oligolectic bees (i.e., Colletes succinctus group and Melitta leporina group) foraging on co-flowering but unrelated host-plants to test this hypothesis. We analyzed floral scent, floral color and chemical composition of pollen from host and non-host plants of these two clades. We did not find evidence for host-plant evolution in the Melitta leporina group driven by one of the assayed floral traits. On the contrary, hosts of the C. succinctus group display similar primary nutritive content of pollen (i.e., amino acids and sterols) but not similar floral scent or color, suggesting that shared pollen chemistry probably mediates saltation in this clade. Our study revealed that constraints shaping floral associations are diverse and clearly depend on species life-history traits, but evidence suggests that pollen chemistry may act as a major floral filter and guide evolutionary host-shifts. [less ▲]

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See detailMesure de l'adhérence et principaux paramètres d'influence
Bissonnette, Benoît; Courard, Luc ULg; Garbacz, ANdrzej

Scientific conference (2017, February 20)

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See detailNotions de compatibilité relatives au développement de l'adhérence
Courard, Luc ULg; Garbacz, Andrzej; Bissonnette, Benoît

Scientific conference (2017, February 20)

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See detailSurface characterization methods for quality control of repair
Garbacz, Andrzej; Bissonnette, Benoît; Courard, Luc ULg

Scientific conference (2017, February 20)

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See detailAdhérence des réparations en béton: concepts, facteurs d'influence et évaluation
Bissonnette, Benoît; Courard, Luc ULg; Garbacz, Andrzej

Scientific conference (2017, February 20)

Detailed reference viewed: 37 (0 ULg)